1. The document discusses the phenomenon of diffraction, where light waves bend and spread out when passing through narrow openings or obstacles. 2. It describes how Huygen's principle explains that each point on a wavefront acts as a secondary source of waves, and the combination of these secondary waves causes diffraction patterns of alternating bright and dark fringes. 3. A key example is single slit diffraction, where light passing through a slit interferes to produce a characteristic pattern on a screen with a bright central band and alternating dark and bright fringes on either side.

1. WEEK 1
DAY 1
CHAPTER :-
DIFFRACTION
THOUGHT OF THE DAY

3. Pondering
Point

4. DIFFRACTION
Learning Objectives:-
• Define Diffraction
• Understand Huygens Principle
of Diffraction.
• Explain Single Slit Diffraction
and its significance
Class activity:-
Demonstrate wave nature of
light
Observe interference pattern in
single slit experiment

5. • Watch the video carefully
https://www.youtube.com/watch?v=4bCUTLWyicM
• Understand the concept of diffraction
• Raise your hands when you know the answer Bonus Point Goes
1.
2.
3.

6. DESTRUCTIVE
INTERFERENCE
REVIEW OF WAVES TERMS
Overlapping of
two waves to
cancel each other
COHERENT
WAVES
Waves having
zero or constant
phase
difference and
frequency
Let’s get started…………
TRANSVERSE
WAVES
All the particles
of waves
oscillate at
right angles to
the direction of
wave
CONSTRUCTIVE
INTERFERENCE
WAVEFRONT
Combination of
two waves to
form larger wave
Straight vertical
lines representing
crests or troughs

7. • Diffraction is the resultant of the wave-nature of light.
• When light waves passes through the edges of
obstacles or a narrow aperture, this causes the waves
to bend and spread out. This phenomenon is called
diffraction.
• This bending results in formation of (bright and dark
fringes) interference pattern which can be seen on the
visualizing screen.
• Wavelets (as in Huygens’ Principle) in a wavefront
interfere with each other.
WHAT IS DIFFRACTION????

10. Single Slit Diffraction Pattern
• All the waves passing through the slit interfere to produce a
diffraction pattern consisting of bright and dark fringes.
• The bright fringes are due to constructive interference, and the
dark areas are due to destructive interference.
• A number “n” represents the order of the bright and dark fringes.
• The intensities of the fringes consist of a central maximum
surrounded by maxima and minima on its either side.
• The central maximum is brighter than the other maxima. The
maxima rapidly decrease as one moves further from the center.

12. 1. What is diffraction?
2. Can particles demonstrate diffraction?
3. What happens when light passes
through a single slit?
4. What is the difference between interference and
diffraction?
5. Does the size of the gap matter when conducting slit
experiments with light? Why?
POP UP QUIZ

13. By the end of the lesson all students
should be:-
 Able to Define Diffraction.
 Understand Huygen’s Principle of
Diffraction.
 Explain Single slit Experiment and
its significance.